How to Cultivate and Care for Bonsai Trees

Learn these botanical basics to fully succeed at planting and caring for your bonsai tree.

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Woman With Bonsai Plant

Bonsai is said to be an art form, but you still have to have some botanical basics to be successful. Bonsai is essentially a tree in a tiny tray; you can even train other types of plants.

Pruning, bending, tying and repotting all help keep the tree compact. Interestingly, if you were to take a bonsai tree and plant it in the landscape, it would grow into a regular-sized tree again. That, of course, defeats the purpose of the art but points out an important aspect. Bonsai are not houseplants. "They grow in nature outdoors, so you really need to keep them in their natural environment," says bonsai expert Dolly Fassio.

Many kinds of plants can be trained to be bonsai. Dolly suggests beginning with a one-gallon, container-grown plant purchased from a reputable nursery, preferably one that specializes in bonsai. "You need to get a tree that's easy to take care of in your area so you know that it will live in your environment."

There are five basic bonsai styles:

The formal upright style highlights a straight trunk

The informal upright style is curved and moving

A slanted trunk flows gracefully to one side, and a variation of this style is called "windswept" for obvious reasons

A half- or semi-cascade drapes over the pot

A full cascade drapes beyond the pot's rim.

The tree itself will often dictate the bonsai style. But don't forget its container. The bonsai pot should blend with the tree and add value and interest. Containers vary in size and price.

The foundation to bonsai is the soil. Bonsai trees need a special soil because they're confined to small pots. Use volcanic mixes containing pumice, fir bark and lava rock for a well-draining soil. The roots hit the sharp edges of the pumice and form more hairlike roots. Fine hairlike roots are better for the tree's health than large roots, says bonsai enthusiast Fred Fassio.

All bonsai need to be repotted periodically. Eventually the roots will grow in and fill the pot. At this point the tree is root-bound and can't absorb enough moisture. Repotting is an art form itself, and this Asian skill calls for Asian tools. Upon pulling the plant out of its pot, Fred uses a chopstick to separate the roots. It's best to repot during the tree's dormancy period since cutting the roots actually encourages new growth. Cut off approximately one-third of the roots from the bottom and around all the sides of the rootball.

In nature, a taproot anchors the tree in the ground. With bonsai, wire does the trick. Thread wire through small holes in the pot. Next, add some soil around the rootball and gently twist the tree downward into the soil to get as much of it into the tree's roots as possible. Tighten the wire over the tree's larger roots, clip away the wire, and tighten it again securely. If the roots are properly wired in the pot, you should be able to pick the tree up by the trunk, and it won't come out of its pot.

Add a few more scoops of soil over the roots and use a chopstick to push the soil down into the tree's roots. This eliminates air pockets that can damage or even kill the tree. The finishing touch is a layer of pre-moistened moss; this helps to add beauty and maintain moisture.